Principle vs ProtoPie: What are the differences?
Principle: Animate Your Ideas, Design Better Apps. It makes it easy to design animated and interactive user interfaces. Whether you're designing the flow of a multi-screen app, or new interactions and animations, it helps you create designs that look and feel amazing; ProtoPie: Interactive prototyping tool for all digital products. ProtoPie is the easiest tool used to turn your UI/UX design ideas into highly interactive prototypes for mobile, desktop, web, all the way to IoT ✔ macOS & Windows ✔ iOS & Android.
Principle and ProtoPie can be primarily classified as "Mobile Prototyping & Interaction Design" tools.